This invention relates to an electrical circuit such as an oscillator or a resonant circuit which is controllable by the application of a control voltage or current to provide a sinusoidal output signal having a voltage of constant amplitude.
Oscillators are, of course, known which generate a sinusoidal output of constant voltage amplitude, the frequency of which can be controlled by a voltage or current so that the relationship between the frequency generated and the control voltage is either fundamentally linear or logarithmic. The frequency range of control of such oscillators may extend over several decades. However, such oscillators are at present achieved in commercial instruments with considerable circuit complexity and often are only operative over a limited frequency range, for example 0.01 Hz to 20 MHz.
Resonant circuits are commonly known in the form of a capacitor/inductance circuit. However, such resonant circuits are not readily adaptable to integrated circuit form and in this field other techniques have to be used to provide resonant circuits.